Carved primarily by the Colorado River over the past six million years,
the Grand Canyon sports vertical drops of 5,000 feet and spans a
445-kilometer-long stretch of Arizona desert. The strata along the
steep walls of the canyon form a record of geologic time from the
Paleozoic Era (250 million years ago) to the Precambrian (1.7 billion
years ago).

The used in this picture scramble was acquired by the Advanced
Spaceborne Thermal Emission and Reflection Radiometer (ASTER)
instrument aboard the Terra spacecraft.
Picture courtesy of NASA/GSFC/MITI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team.